Physiology Exam 4

Functions of the respiratory system

Exchange of O2 and CO2 between the atmosphere and the blood

Homeostatic regulation of body pH

Protection from inhaled pathogens and irritating substances

Vocalization

Respiratory pump: enhances venous return

Pathway of air flow

Pharynx → larynx → trachea (windpipe)

Primary bronchi → bronchioles

Larynx contains the ____

Vocal chords

What do airways do to help the air?

Warm, humidify, and filter inspired air

Type I alveolar cells

Gas exchange

Type II alveolar cells

Produce surfactant

The right lung has ___ lobes, and the left lung has ____

Three, two

Pleural membrane

Double-walled, encloses lungs

Pleural cavity

Interior of the pleural sac

Pleural fluid

Lowers friction between membranes

Holds tight agains the thoracic wall

Components of the thoracic cage

Spine and rib cage

Diaphragm, intercostal muscles, sternocleidomastoids, scalene

Accessory muscles of inspiration

Contract only during forceful inspiration

Sternocleidomastoid, scalenes

Muscles of active expiration

Contract only during expiration

Internal intercostal muscles, abdominal muscles

Major muscles of inspiration

Contract every inspiration; relaxation causes passive expiration

External intercostal muscles, diaphragm

What are the three aspects used for breathing mechanics?

Atmospheric pressure

Intra-alveolar pressure

Intrapleural pressure

How will intra-alveolar pressure change during inspiration?

Decreases

How will intra-alveolar pressure change during expiration?

Increases

Why is intrapleural pressure sub atmospheric?

Negative pressure in the pleural cavity keeps the lungs inflated

When will ventilation rate increase?

Exercise, sympathetic activation

When will ventilation rate decrease?

Parasympathetic activation

Breathing is all based on _____

Pressure gradient

What happens during inspiration?

Chest wall muscles contract → elevated ribs and diaphragm moving downward → negative intrapleural pressure

What happens during expiration?

Lungs deflate passively (at rest) because of elastic recoil and muscle relaxation

How will parasympathetics impact resistance?

Bronchoconstriction

Bronchoconstriction

Decrease in the radius of bronchioles

How will sympathetics impact resistance?

Bronchodilation

Bronchodilation

Increase in bronchiolar radius

Larger bronchiolar radius →

Less resistance/more airflow

How will CO2 impact airflow to blood flow?

CO2 increases blood flow by causing vasodilation

How will O2 impact airflow to blood flow?

O2 causes decreased blood flow and vasodilation

Compliance

How much effort is required to stretch or distend the lung

Elastic recoil

How readily the lungs rebound after having been stretched

How will pulmonary surfactant decrease surface tension?

Decreases work of breathing (alveoli open easily with each breath)

Tidal volume

Volume of air during a normal breath

Inspiratory reserve volume

Extra volume taken in during maximum inspiration

Expiratory reserve volume

Extra volume moved out during maximum expiration

Residual volume

Minimum of air left in lungs after maximal expiration

Total lung capacity

Maximum volume of air that lungs can hold

Vital capacity

The full amount of air a lung moves during maximum inspiration and maximum expiration, not including residual volume

Anatomic dead space

Volume of gas not used in gas exchange (1/3 of each breath)

What type of transport mechanism will gas exchange utilize?

Alveolar Po2 and Pco2

Po2 and Pco2 gradients across the pulmonary capillaries

How will surface area impact gas exchange?

A larger surface will increase gas exchange

How will thickness impact gas exchange?

Thinner membranes allow for gas molecules to travel faster

How will the diffusion constant impact gas exchange?

Directly relates to the speed of movement of gas (i.e. higher constant → faster movement)

Gas exchange across the systemic capillaries occurs down ____

Partial pressure gradients

Most oxygen is transported bound to ____

Hemoglobin

Hemoglobin acts as a storage depot for ___

Oxygen

Cerebral cortex

Voluntary control of breathing

Respiratory centers in the brain stem

Medulla, pons

Medulla respiratory center

Inspiratory and expiratory neurons (gross motor)

Pons respiratory center

“fine-tuning” influence over medulla → smooth inspiration/expiration (fine motor)

Decreased RR is a response to ____

Decreased CO2 levels

Increased pH

Increased RR is a response to _____

Decreased O2 levels

Increased CO2 levels

Decreased pH

Key functions of the renal system

Maintain H2O balance in the body

Maintain proper tonicity of body fluids

Regulate the concentration of electrolytes

Maintain optimal blood (plasma) volume

Blood pH homeostasis

Eliminate wastes of bodily metabolism

Produce renin and erythropoietin

Activate vitamin D

What % of CO goes to the renal artery?

25%

Nephron

Individual unit of filtration

Nephron functions

Removal of nitrogenous wastes (urea)

Balance electrolytes and blood volume

Produces urine

Vascular components of the nephron

Glomerulus

Afferent arterioles

Efferent arterioles

Peritubular capillaries

Tubular component of the nephron

Bowman’s capsule

Proximal tubule

Loop of Henle

Distal tubule

Collecting duct

Glomerulus

Filtration, capillary BP

Bowman’s capsule

Catches filtration from glomerulus

Proximal tubule

Most of filtrate reabsorption

Loop of Henle

Concentration of urine

Descending loop of Henle

H2O reabsorption only

Ascending loop of Henle

Sodium reabsorption only

Renal processes

1. Glomerular filtration - nonselective

2. Tubular reabsorption - tubule → bloodstream

3. Tubular secretion - selective: bloodstream → tubule

4. Urine secretion

What is the major force that causes filtration?

Capillary BP

Changes in GFR result in ____

Changes in glomerular capillary blood pressure

Why is reabsorption highly selective?

To maintain proper fluid composition and volume

What transport mechanisms are involved in tubular reabsorption?

Passive and active transport

Na+-K+ pump

What will stimulate aldosterone to be released to the kidneys for sodium reabsorption?

Angiotensin II

What organ releases ANP?

Atria

What organ releases BNP?

Ventricles

How will glucose and amino acids be reabsorbed?

Secondary active transport

How will glucose impact maximum resorption rate?

As glucose concentration increases in the blood, the maximum resportion rate also increases

Why is glucose in the urine a sign of diabetes?

Glucose in the urine means that the kidneys are unable to reabsorb all the glucose causing the excess to be excreted in the urine

In addition to sodium, what other electrolytes will be resorbed?

K+ and H+

What happens to unwanted waste products?

They are filtered through the nephron

What ion is controlled by aldosterone?

K+

What ion is controlled by the acid-base balance?

H+

What depends on the relative amount of water compared to solutes?

Tonicity

What gland releases vasopressin?

Pituitary

What’s an AKA for vasopressin?

Antidiuretic hormone

What stimulates vasopressin?

Low blood volume and concentrate blood (increased blood tonicity) activate hypothalamic osmorecptors

Role of the bladder

Collects and stores urine until micturition

What is another name for micturition?

Urination

What is “normal” pH in the human body?

7.38-7.42

What happens if pH changes?

Changes can alter three-dimensional structure of proteins

Impaired enzymatic reactions

What are the two buffering systems?

Bicarbonate and phosphate

Which buffering system deals with ICF?

Bicarbonate buffering system

Which buffering system deals with ECF?

Phosphate buffering system

What will the respiratory system regulate?

Regulates H+ by controlling the rate of CO2 removal

Change pulmonary ventilation and rate of excretion of CO2

How will the kidneys manipulate acid levels?

By varying the extent of H+ secretions

What determines if bicarbonate is released to buffer the blood?

Depends on the plasma H+

Renal/metabolic acidosis

Excrete H+ ions and retain HCO3-

Renal/metabolic alkalosis

Retain H+ ions and excrete HCO3-

Respiratory/pulmonary acidosis

Increased ventilation releases CO2

Respiratory/pulmonary alkalosis

Decreased ventilation retains CO2

What is the function of the digestive system?

Transfer nutrients, water, and electrolytes from food into the body’s internal environment

Basic digestive process

Motility → secretion → digestion → absorption